You can retake individual modules if you fail one. This is called the modular exam system.
Don’t aim for "perfection" – aim for Kommunikationsfähigkeit (communication ability). At B1, fluency and clarity matter more than advanced grammar. zertifikat b1 goethe
You are no longer a beginner. You can express yourself without much hesitation, even if vocabulary or grammar isn't perfect. You can retake individual modules if you fail one